In oil and gas producing facilities, a large amount of oil contaminated liquids is produced. Such liquids include for instance produced or processed water containing oil residues and solids, and they are commonly purified by use of systems including compact floatation units (CFUs).
In compact floatation units (CFUs), purification of the contaminated liquid is obtained by bringing the liquid into contact with gas bubbles. The gas bubbles attach to oil droplets in the liquid creating agglomerates having a density lower than the density of the oil droplets.
In prior art CFU systems, the gas bubbles are commonly obtained by either dissolved air floatation (DAF) or induced gas floatation (IGF), or a combination wherein the gas bubbles formed by DAF is due to residual gas in the liquid to be purified.
The purpose of the present invention is to provide an improved compact floatation unit.